model fields get_prep_value should accept string

One of the cases when the value is a string is migration generation with
default value.

Fix: #51

Author: smacker

filebrowser/fields.py

@@ -1,6 +1,8 @@
 # coding: utf-8
 import os
 
+from six import string_types
+
 from django import forms
 try:
     from django.urls import reverse
@@ -111,7 +113,7 @@ def from_db_value(self, value, expression, connection, context):
         return self.to_python(value)
 
     def get_prep_value(self, value):
-        if not value:
+        if not value or isinstance(value, string_types):
             return value
         return value.path
 
@@ -248,8 +250,8 @@ def to_python(self, value):
             return value
         return FileObject(value, site=self.site)
 
-    def get_db_prep_value(self, value, connection, prepared=False):
-        if not value:
+    def get_prep_value(self, value):
+        if not value or isinstance(value, string_types):
             return value
         return value.path
 

tests/test_fields.py

@@ -0,0 +1,35 @@
+# coding: utf-8
+
+from tests import FilebrowserTestCase as TestCase
+
+from six import string_types
+
+from filebrowser.base import FileObject
+from filebrowser.fields import FileBrowseField
+
+
+class FileBrowseFieldTests(TestCase):
+    path_to_file = "/path/to/file.jpg"
+
+    def test_to_python(self):
+        field = FileBrowseField()
+
+        # should deal gracefully with any of the following arguments:
+        # An instance of the correct type, a string, and None (if the field allows null=True)
+        values = [FileObject(self.path_to_file), self.path_to_file]
+        for v in values:
+            actual = field.to_python(v)
+            self.assertIsInstance(actual, FileObject)
+            self.assertEqual(actual.path, self.path_to_file)
+        self.assertEqual(field.to_python(None), None)
+
+    def test_get_prep_value(self):
+        field = FileBrowseField()
+
+        # similar to to_python() should handle all 3 cases
+        values = [FileObject(self.path_to_file), self.path_to_file]
+        for v in values:
+            actual = field.get_prep_value(v)
+            self.assertIsInstance(actual, string_types)
+            self.assertEqual(actual, self.path_to_file)
+        self.assertEqual(field.to_python(None), None)